Slide Bearings Type E For Shaft Diameter Range 80-355 mm Main ...

Bearing calculation
When the operating conditions
are given by the customer,
each bearing supplied by us is
designed and checked on the
basis of hydrodynamic and
thermal calculations with the
aid of a computer. The values
to be used e.g. speed, size
and direction of load, grade of
oil viscosity and ambient temperature
are standard factors
for calculating the behaviour.
We must therefore ask for correct
information for the values
listed in our „Enquiry for Slide
Bearings“ form.
The bearing temperature and
minimum thickness of oil film
determine the reliability of a
slide bearing.
To make it possible for users
to select a bearing in the project
stage, graphs are given on
pages 14 and 15 showing, for
lubricatin with oil rings, the
dependence of the average
bearing temperature on the
speed.
With oil ring lubrication, an
ISO VG 32 lubricating oil is
chosen as a parameter in
order to show the widening of
the range of application at
high speeds.
Uncompleted curves in the
low speed range show that
the minimum thickness of oil
film is not reached here (the
remedy is to select an oil with
higher viscosity).
If the graph shows that the
allowable bearing temperatureis
already exceeded as a
result of the heat generated in
the journal bearing, then one
High-voltage threephase generator
Siemens new series
H-modul with RENK Slide
Bearing EF.
(Photo: Siemens AG, Erlangen)
of the alternatives listed under
the section „Heat dissipation“
is to be used.
As the majority of slide bearings
used in the heavy
machine building industry
operate at speeds up to
3600 RPM with a specific load
pressure of approx. 0.5 to
2.5 N/mm2 , the curves have
been plotted for 1.0 N/mm2 and 2.0 N/mm2. With a specific load of more
than 2,5 N/mm2 a computer
calculation should be carried
out inorder to determine the
grade of oil required (higher
viscosity). Higher speeds
and/or shmaler specific loads
could require bearing shells
with two- or four-lobe bores or
radial tilting segments to be
installed.
The graphs on pages 16 and
17 give the oil throughput for
lubrication by a circulating oil
system or by means of a circulating
pump for:
a) E-Type bearing with shells
with plain cylindrical bore
b) E-Type bearing with shells
with two- or four-lobe
bore, journal tilting pads
c) additional oil throughput
for E-Type bearing with
taper land faces in the
thrust part
d) additional oil throughput
for E-Type bearing with
RD thrust pads.
Stability
In order to be able to judge
the influence of slide bearings
on the stability of high-speed
rotors, the anisotropy of the
lubricating film is taken into
consideration by specifying 4
elasticity and 4 damping values
and the quasi-orthotropy
of the bearing housing by
specifying the horizontal and
vertical elasticity constants.
RENK Hannover can, on
request, calculate the critical
speed of the shaft taking into
account the properties of the
oil film, the mass and stiffness
of the bearing housing and the
foundations. With electric
machines the magnetic elasticity
constant may be included.
When using the E-bearings,
please also consult our
„Manual for the application of
RENK Slide Bearings“ as well
as our „Instructions for
assembly, operation and maintenance“
available for every
special design.
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